Experiments in this proposal are designed to determine the nature of control of enzymatic interconversion of phylloquinone and phylloquinone-2, 3-epoxide, reactions which require separate enzymes from liver microsomes. The conversion of microsomal precursor protein to prothrombin will be studied. Both epoxidation and prothrombim formation require, in addition to microsomes, a heat labile macromolecular and a heat stable low molecular weight component of the cytosol. Techniques of protein purification will be utilized in order to separate components of each enzymatic reaction as well as those required for prothrombin formation. This will allow a more accurate study of the kinetics and inhibition of each enzyme and the mechanism of regulation of the interconversion of vitamin and epoxide and if this interconversion is coupled to the production of prothrombin.